1. Field of the Invention
This invention relates to a body fluid bag and a method for the treatment of blood. More particularly, it relates to a body fluid bag for storing a body liquid such as blood and marrow liquid and being subjected to centrifugal operation, a method for ideally adding for admixture the preserved solution of erythrocyte remaining after the separation of concentrated erythrocyte component from blood to the concentrated erythrocyte component.
2. Description of the Prior Art
In the operation of blood transfusion, the system relying on a procedure which comprises separating the blood extracted from donors into blood components as by means of centrifugation and using for the transfusion only those of the separated blood components which are necessary for particular donees is now prevailing for the sake of promoting effective use of blood and lessening the burden on the part of donors. This componential transfusion of recent introduction has been serving the purpose of permitting effective use of blood as compared with the conventional whole blood transfusion.
In the componential transfusion just mentioned, the closed and sterilized blood bags of the triple type or quadruple type illustrated in FIG. 11 and FIG. 12 are used most widely. These blood bags 5, 6 generally comprise a relatively large parent bag (blood collection bag) 121 serving to collect whole blood and having an anticoagulant liquid for hindering coagulation of blood enclosed therein, one or two daughter bags 123, 124 connected to the parent bag 121 through the medium of a connecting tube 122 provided above the parent bag 121 and adapted to transfer and seal in a blood component, and a preserving liquid bag 125 connected to the parent bag 121 through the medium of the connecting tube 122 provided above the parent bag 121 and having enclosed therein a erythocyte preserving liquid to be added, subsequently to the separation of blood components, to the erythrocyte in the parent bag 121 and enabled to permit safe preservation of erythrocyte for a long time.
After the blood has been collected in the blood bag of this construction from a donor, the whole blood is generally stored in the unmodified form therein or it is separated into blood components and stored as such in preparation for actual use. The separation is effected by sedimentation or centrifugation. As a result, the blood is separated into an upper layer of blood plasma and a lower layer of erythrocyte or into an upper layer of blood plasma, an intermediate layer of buffy coat (a thin soft film layer containing white blood corpuscles and blood platelets), and a lower layer of erythrocyte.
In any event, the erythrocyte is are left in the parent bag 121. The erythrocyte thus separated are combined with the erythrocyte preserving liquid when this liquid is transferred from the preserving liquid bag 125 via the connecting tube 122 to the parent bag 121. In the parent bag 121, the resultant blend is stored as a red blood preparation useful as for transfusion.
In the conventional method for the treatment of blood which is operated as described above, however, the erythrocyte preserving liquid is destined to be added downwardly to the parent bag from the upper side thereof. The erythrocyte preserving liquid has a lower specific gravity than the erythrocyte and the erythrocyte is are pressed in a highly densified state against the bottom part of the parent bag by the centrifugal force exerted thereon in the process of centrifugal separation. The erythrocyte preserving liquid in its unmodified form, therefore, cannot be thoroughly mixed with the erythrocyte and, on being admixed therewith somehow or other, often gives rise to floccules (such as of leukocyte, blood platelets, and fibrins), and inevitably entails the problems of degrading the quality of the erythrocyte preparation to be eventually obtained. To preclude this problem, therefore, the conventional method has been required to subject the erythrocyte to the action of stirring during or immediately after the addition of the erythrocyte preserving liquid.
In order to improve the defects of such bag, a blood bag provided a zonal partition part for dividing an interior of the bag body into two spaces between two ports formed at an upper portion of the bag body (EP-A-O 484 751).
The partition part of the blood bag is obtained by sealing (melting) resin sheets which constitute the bag body from upper portion of the bag body to a half portion of the bag body with a long zonal shape parallely with a side portion of the bag body, but the lower end portion is a cut shape (See FIG. 2) and the width of the partition part is constant, so sealing strength is low. Therefore, there are defects that when the blood bag is subjected to centrifugation after filling blood into the blood bag, inner pressure of lower portion of the blood bag of the blood bag increases, and expands, so if stress concentrates to lower end region of the partition part, pealing or crack generates at this portion, and finally the bag body sometimes explodes.
Further, the distance between a center of the partition part of the blood bag and side portion of the bag body near the center, i.e., the width of a channel wherein blood goes through is defined not more than 7 mm, so there are difects that the channel is apt to blockade by deformation of the side portion of the bag under the condition of expansion of the blood bag after centrifugation, and even if such blockade does not generate, discharging rate of erythrocyte is low because of too narrow width of the channel.
Furthermore, in the blood bag, two valves provided at an upper portion of the bag and connected with tubes for discharging plasma and erythrocyte project in two spaces PG,6 divided by the partition part, and the operation for opening the valves is carried out by pinching the valves together with the bag, so there are problems that vibration (liquid fluidization) is transferred and boundaries of each separated layers is disordered, and as a result, recovery ratio of erythrocyte decreases and mixing ratio of leukocyte in the plasma increases.
Therefore, an object of the present invention is to provide a body fluid bag which is suitable for centrifugal separation, has no trouble about breakage of the partition part, is easy to produce and to handle, can make discharge a separated component without using a specific device, can make obtain the same or more recovery ratio or separation ratio of the separated component compared with a conventional method even if recovery of the separated component is carried out by using a conventional simple device, and can make sufficient discharging rate of the separated component.
The present invention, conceived in the urge to protect the conventional method of blood treatment against the problem of frequently entailing the occurrence of floccules in the erythrocyte preparation, has as an object thereof the provision of a method for the treatment of blood which can produce a erythrocyte preparation of high quality without entailing the occurrence of floccules.